diff options
| author | Ackerley Tng <ackerleytng@google.com> | 2026-09-10 16:55:43 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2026-09-22 07:28:30 -0700 |
| commit | 856852ef2108fd4e70f29d450487fe15324c647c (patch) | |
| tree | 11f3e5586b41558ad4b76a33b2d4c44f51530c92 | |
| parent | 6fa1dab756fd49d4b3162a68775de3aeec78646e (diff) | |
KVM: guest_memfd: Return early if range already has requested attributes
Provide a function to check that a range has given attributes.
Optimize setting memory attributes by returning early if all pages in the
requested range already have the requested attributes.
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Tested-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://patch.msgid.link/20260910-gmem-inplace-conversion-v13-17-dd6fbf94f4e1@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | virt/kvm/guest_memfd.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 5b6b58ea2acb..8eedff42a96f 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -99,6 +99,24 @@ static bool kvm_gmem_is_shared_mem(struct inode *inode, pgoff_t index) return !kvm_gmem_is_private_mem(inode, index); } +static bool kvm_gmem_range_has_attributes(struct inode *inode, + pgoff_t index, size_t nr_pages, + u64 attributes) +{ + struct maple_tree *mt = &GMEM_I(inode)->attributes; + pgoff_t end = index + nr_pages - 1; + void *entry; + + lockdep_assert(mt_lock_is_held(mt)); + + mt_for_each(mt, entry, index, end) { + if (kvm_gmem_get_attributes(inode, entry) != attributes) + return false; + } + + return true; +} + /* * Returns a locked folio on success. The caller is responsible for * setting the up-to-date flag before the memory is mapped into the guest. @@ -675,12 +693,15 @@ static int __kvm_gmem_set_attributes(struct inode *inode, pgoff_t start, pgoff_t end = start + nr_pages; struct maple_tree *mt; struct ma_state mas; - int r; + int r = 0; mt = &gi->attributes; filemap_invalidate_lock(mapping); + if (kvm_gmem_range_has_attributes(inode, start, nr_pages, attrs)) + goto out; + mas_init(&mas, mt, start); r = kvm_gmem_mas_preallocate(&mas, attrs, start, nr_pages); if (r) { |